"We know time is valuable, so we asked lots of Googlers for their tips and tricks on how they make the most of Gmail, and we combined the best of these into a guide at www.gmail.com/tips, cheekily entitled "Become a Gmail Ninja." The tips are categorized into ninja belts (white, green, black and master ) based on how much mail you get each day.

For a handy reference that you can pin to your wall or keep on your desk, we even made a printable version of the guide where all the tips fit on one page front and back."